enum {
  M3PI_CMD_DEVICE_SIG = 0x81,
  M3PI_CMD_SENSORS_RAW = 0x86,
  M3PI_CMD_SENSORS_CALIBRATED = 0x87,
  M3PI_CMD_TRIMPOT = 0xB0,
  M3PI_CMD_BATT_MILLIVOLTS = 0xB1,
  M3PI_CMD_PLAY_MUSIC = 0xB3,
  M3PI_CMD_CALIBRATE = 0xB4,
  M3PI_CMD_RESET_CALIBRATION = 0xB5,
  M3PI_CMD_LINE_POS = 0xB6,
  M3PI_CMD_CLEAR_LCD = 0xB7,
  M3PI_CMD_PRINT = 0xB8,
  M3PI_CMD_LCD_XY = 0xB9,
  M3PI_CMD_AUTO_CALIBRATE = 0xBA,
  M3PI_CMD_START_PID = 0xBB,
  M3PI_CMD_STOP_PID = 0xBC,
  M3PI_CMD_MOTOR_LEFT_FORWARD = 0xC1,
  M3PI_CMD_MOTOR_LEFT_BACKWARD = 0xC2,
  M3PI_CMD_MOTOR_RIGHT_FORWARD = 0xC5,
  M3PI_CMD_MOTOR_RIGHT_BACKWARD = 0xC6,
};
